1. Field of the Invention
Aspects of the present invention relate to a burner for heating a reformer that generates hydrogen, and more particularly, to a reformer burner that has increased combustion efficiency.
2. Description of the Related Art
A fuel cell is a system that directly transforms the chemical energy of oxygen and hydrogen from hydrocarbon group materials such as methanol, ethanol, or natural gas into electrical energy.
A fuel cell system includes a fuel cell stack and a fuel processor (FP) as main components, and includes a fuel tank and a fuel pump as supplementary components. The fuel cell stack is a stacked structure which comprises a few to many unit cells, each unit cell being composed of a membrane electrode assembly (MEA) and a separator.
FIG. 1 is a block diagram illustrating a configuration of a fuel cell system 100. Referring to FIG. 1, a fuel 105 that contains hydrogen atoms is reformed into hydrogen gas in a fuel processor 102, and the hydrogen gas is supplied to a fuel cell stack 130. In the fuel cell stack 130, electrical energy is generated by an electrochemical reaction between the hydrogen and oxygen.
The fuel processor 102 includes a desulphurizer 110 and a hydrogen generator 120. The hydrogen generator 120 includes a reformer 122 and a shift reactor 124.
The desulphurizer 110 removes sulfur from the fuel 105 so that a catalyst of the reformer 122 and the shift reactor 124 are not poisoned by a sulfur compound.
The reformer 122 generates hydrogen, carbon dioxide, and carbon monoxide, through the reformation of a hydrocarbon material. Carbon monoxide can poison the catalytic layers of the electrodes in the fuel cell stack 130. Therefore, a reformed fuel should not be directly supplied to the fuel cell stack 130. Accordingly, the shift reactor 124 that removes carbon monoxide from the fuel is required. The shift reactor 124 may reduce the content of the carbon monoxide in the reformed fuel to less than 10 ppm.
A reformer burner (not shown) heats an inner space (combustion chamber) of the reformer 122 to approximately 750° C. to reform a hydrocarbon that passes the catalyst of the reformer 122.
FIG. 2 is a cross-sectional view of a reformer 10. Referring to FIG. 2, a reformer burner 11 having a pipe shape is installed in a combustion chamber 12, which is an inner space of a reformer 10. A reformer catalyst 13 is disposed on the outer surface of the combustion chamber 12. A fuel and air supplied to the reformer burner 11 are ignited using an ignition source (not shown), and combustion gases are exhausted out through a gas outlet 15. It is advantageous to the reforming efficiency of a hydrocarbon for the reformer catalyst 13 to be uniformly heated to a temperature of 700 to 750° C.
FIG. 3 is a diagram showing a simulation result of a temperature profile of the reformer 10 of FIG. 2. Referring to FIG. 3, when the reformer burner 11 has a pipe shape, the temperature range of the reformer catalyst 13 is from 600 to 825° C., and the large temperature difference reduces the reforming efficiency of the reformer 10.